1. Field of the Invention
The present invention relates to a method for producing a plate-like alumina powder.
2. Description of the Related Art
PTL 1 discloses an oriented alumina sintered body produced using a plate-like alumina powder as part of raw materials and shows that the orientation of the alumina sintered body improves corrosion resistance and heat resistance. However, to obtain high corrosion resistance and heat resistance, it is necessary to reduce the amount of impurities in the sintered body, and there is a need for a plate-like alumina powder with higher purity, in order to achieve a further improvement in these properties.
A high-purity dense alumina sintered body is known to have optical translucency. PTL 2 discloses optical translucency of a ceramic polycrystal having a triclinic, monoclinic, orthorhombic, tetragonal, trigonal, or hexagonal crystal structure. PTL 2 shows that an oriented alumina sintered body produced using a plate-like alumina powder as part of raw materials can have sufficient heat resistance and high in-line transmittance. However, it is generally known that, to achieve high optical translucency in an alumina sintered body, the purity of the alumina sintered boy must be high. Therefore, a high-purity plate-like alumina powder is needed. For example, methods described in PTL 3 to PTL 6 and NPL 1 are known as methods for producing a plate-like alumina powder.